Muda River

154 Pages·2006·21.13 MB·English

KERAJAAN MALAYSIA

JABATAN PENGAIRAN DAN SALIRAN MALAYSIA
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Pusat Penyelidikan Kejuruteraan Sungai dan Saliran Bandar
(REDAC)
Kampus Kejuruteraan, Universiti Sains Malaysia
Seri Ampangan, 14300 Nibong Tebal, Pulau Pinang
Tel : [phone] Fax : [phone]

September, 2006
KERAJAAN MALAYSIA

JABATAN PENGAIRAN DAN SALIRAN MALAYSIA

DESIGN OPTION OF THE FLOOD MITIGATION PLAN
OF SG. MUDA, SUNGAI MUDA, KEDAH

Draft Final Report
September, 2006

Prepared by :

Prof. Pierre Y. Julien (Colorado State University, USA)
Prof. Madya Dr. Aminuddin Ab. Ghani
Prof Dr. Nor Azazi Zakaria
Prof. Madya Dr. Rozi Abdullah
Chang Chun Kiat
Rosmaliza Ramli
Joseph Dinor
Asnol Adzhan Abd. Manap
Mohd Fazly Yusof

Pusat Penyelidikan Kejuruteraan Sungai dan Saliran Bandar (REDAC)
Kampus Kejuruteraan, Universiti Sains Malaysia
Seri Ampangan, 14300 Nibong Tebal, Pulau Pinang, Malaysia.
PENGHARGAAN

Pihak Juruperunding ingin mengucapkan setinggi-tinggi penghargaan kepada :

BAHAGIAN TEBATAN BANJIR
JABATAN PENGAIRAN DAN SALIRAN MALAYSIA

BAHAGIAN HIDROLOGI DAN SUMBER AIR
JABATAN PENGAIRAN DAN SALIRAN MALAYSIA

JABATAN PENGAIRAN DAN SALIRAN
NEGERI KEDAH DARUL AMAN

JABATAN PENGAIRAN DAN SALIRAN
NEGERI PULAU PINANG

JABATAN PENGAIRAN DAN SALIRAN
RANCANGAN TEBATAN BANJIR SUNGAI MUDA

USAINS HOLDING SDN. BHD.
UNIVERSITI SAINS MALAYSIA

di atas segala kerjasama yang diberikan semasa projek ini dijalankan.

Pusat Penyelidikan Kejuruteraan Sungai dan Saliran Bandar (REDAC)
Kampus Kejuruteraan, Universiti Sains Malaysia
Seri Ampangan, 14300 Nibong Tebal, Pulau Pinang, Malaysia.
DESIGN OPTION OF THE FLOOD MITIGATION PLAN
OF SG. MUDA, SUNGAI MUDA, KEDAH

CONTENTS

Page

EXECUTIVE SUMMARY v

CHAPTER 1 INTRODUCTION 1

1.1 Background 1
1.2 Objectives 1
1.3 Scope of Work 2

CHAPTER 2 SITE VISITS AND RECENT FLOODS 3

2.1 Site Observations 3
2.2 Rainfall Distribution 11
2.3 Flood Frequency Analysis 13

CHAPTER 3 PAST STUDIES OF SG. MUDA 17

3.1 JICA (1995) 17
3.1.1 Objectives of the Study 17
3.1.2 Study Area 18
3.1.3 Climate 18
3.1.4 River Morphology 19
3.1.1.1 River System 19
3.1.1.2 River Channel Profile 19
3.1.1.3 Channel Flow Capacity 20
3.1.1.4 River Water Quality 20
3.1.1.5 River Flow Regime 23
3.1.1.6 Riverbed Material 24
3.1.1.7 River Bed Load 24
3.1.1.8 Fauna and Flora 24
3.1.5 Flood Prone Areas and Types of Flood 26
3.1.5.1 Maximum Flood Recorded 26
3.1.5.2 Probable Rainfall and Probable Flood Runoff
Discharge 27
3.1.5.3 Existing Flood Mitigation Facilities 29
3.1.5.4 River Sand Mining 30

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3.2 Abdullah (2002) 64
3.2.1 Study Reach 64
3.2.2 Hydrological data 64
3.2.3 Field Data Collections 65
3.3 JPZ (2000) 75
3.3.1 Configuration of Flood Mitigation Alternatives 75
3.3.2 Selection of Flood Mitigation Alternative 75

CHAPTER 4 HYDROLOGICAL MODELLING 81

4.1 HEC-HMS Modelling 81
4.1.1 Hydrological Data 81
4.1.2 Rainfall 81
4.1.3 Water Level and Streamflow 81
4.1.4 Calibration and Validation 83
4.1.5 Design Hydrographs 90
4.2 HEC-RAS Modelling 94
4.2.1 Introduction 94
4.2.2 Geometry Data 95
4.2.3 Stage Hydrograph Data 95
4.2.4 Hydrograph 95
4.2.5 Calibration 96
4.2.6 Simulation 103

CHAPTER 5 RIVER MODELLING 105

5.1 River Sediment Data Collection 105
5.2 Flow Discharge and Sediment Load Measurements 109
5.3 Sediment Transport Modelling 114
5.3.1 Geometry Data 114
5.3.2 Tidal Record 115
5.3.3 S-Curve 116
5.3.4 Hydrograph 117
5.3.5 Calibration 117
5.3.6 Simulation 119

CHAPTER 6 PROPOSED DESIGN CRITERIA 125

6.1 Regional Storage 125
6.2 Natural River Design 129
6.2.1 Review of the Rainfall Data 129
6.2.2 Runoff Discharge and Stage Records 130
6.2.3 Changes in Alluvial River Geometry 132
6.2.4 Design Criteria for the Flood Control Remediation Plan 135
6.2.5 Summary of Specific Design of the Proposed Structures 142

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CHAPTER 7 CONCLUSIONS AND RECOMMENDATIONS 145

7.1 Conclusions 145
7.2 Recommendations 147

REFERENCES 149
iii
Executive Summary

USAINS HOLDING Sdn Bhd through River Engineering and Urban Drainage
Research Centre (REDAC) has been appointed by Jabatan Pengairan dan Saliran
Malaysia to carry out DESIGN OPTION OF THE FLOOD MITIGATION PLAN
OF SG. MUDA, SUNGAI MUDA, KEDAH beginning 1 April 2006 for a period of six
months.

The Draft Final Report presents seven chapters as follows:

CHAPTER 1 INTRODUCTION

CHAPTER 2 SITE VISITS AND RECENT FLOODS

CHAPTER 3 PAST STUDIES OF SG. MUDA

CHAPTER 4 HYDROLOGICAL MODELLING

CHAPTER 5 RIVER MODELLING

CHAPTER 6 PROPOSED DESIGN CRITERIA

CHAPTER 7 CONCLUSIONS

The Flood Control Remediation Plan (FCRP) of Sg Muda has been reviewed with the
perspective to possibly enhance the proposed design. The objectives of this review are
to: (1) ensure that design cross-sections and alignment of the main river channel are
economic, effective and environmentally sound; (2) propose alternative designs for
identified locations to meet the above requirements; and (3) examine the long term
river behaviour through model studies to minimise expensive repair works in future
resulting from the new alignment.

The current bund height proposed by JPZ is based on a 50 year ARI design discharge of
1,815 cumecs plus freeboard. This design is found to be highly conservative and will
pass flows with period of return far in excess of 100 years. The main conclusion of this
review is that the design of the bund height should be based on the 2003 flood
discharge of 1,340 cumecs plus a one meter freeboard. The proposed channel widening
in Alternative 2 of the JPZ report also appears not to be necessary. If retained, channel
widening should correspond to significant lowering of the bund height.

A plan to address the sand and gravel mining issues on Sg Muda is also strongly
recommended to ensure: (1) stability of the proposed river bank protection structures;
(2) stability of the bridge piers at Ladang Victoria; and (3) operations of irrigation
pumping stations. Channel realignment is proposed at two sites to increase flood
conveyance and further lower the proposed bund height. In-stream mining should not
v
be allowed between Ladang Victoria and the Muda barrage. Off-stream mining at a
minimum distance of 50 m from the river bank should be permitted instead.

With a design discharge reduction of 25%, this study shows the potential for very
significant cost savings of this FCRP for Sg. Muda. A more detailed analysis of the
reduced bund elevation should include the effects of the reduced design flood discharge
and the proposed realignment. Channel widening is not recommended, but if retained,
the bund heights should be lowered accordingly. The details on the locations and sand
mining volumes extractable from off-stream mining activities should be examined.
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Chapter 1

Introduction

1.1 Background

Urbanization normally brings about an increase in the discharge of a river due to
increase in impervious areas. As a result, the sediment transporting capacity of the river
also increases causing changes to the river equilibrium. Recurrence of flooding has
been linked to the high rate of sedimentation in the river channel. Failures of bank
protection structures frequently occur during and after the construction of a flood
mitigation project. Causes of the failures are numerous and river bed degradation or
erosion resulting in the instability of the structures in a river is the pertinent one.
Erosion and sedimentation in rivers involve a dynamic process resulting from the
interaction between the flowing water and sediment bed. An understanding of this
interaction which causes sediment movement and hence cross-sectional changes is
important to control the erosion and sedimentation within allowable limits to ensure the
stability of the river channel.
1.2 Objectives

Sg. Muda experiences floods almost every year, each differing only in their
magnitude. The October 2003 flood saw 45,000 people affected with catastrophic
damages. At the upstream end of Sg. Muda is the Muda dam which acts as an extra
storage for the Pedu dam. The two dams are part of the MUDA irrigation scheme.
With the northern states being a water deficit area, the first flood mitigation option
was to increase the storage volume of Muda dam. This idea however, was not well
received by Kedah state government. Therefore the next best option is the rapid
conveyance of the flood water into the sea.

The valley or flood plain is part of the river system. Over the years, large numbers of
inhabitants have encroached into the flood plain. To make matters worse many of the
dwellings are built close to the river. Sg Muda is also a major source of sand for the
northern region. A study by JICA in 1995 showed that total sand being excavated
from the river from more than 100 mining locations far exceeded the total yield of
sand by the river (in the region of 100 times). As such the river bed had severely
degraded throughout its length with many stretches of river banks also badly eroded.

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The government requires consultancy services to carry out a review study of the on-
going Sg. Muda flood mitigation project to achieve the following objectives:

(i) Ensure that design cross-sections and alignment of the main river channel
are economic, effective and environmentally sound;

(ii) Propose alternative designs for identified locations to meet the above
requirements;

(iii) Examine the long term river behaviour through model studies, to minimise
expensive repair works in future resulting from the new alignment.

1.3 Scope of Work

The Consultant shall conduct a review of the following:

(a) Rainfall data in space and time leading to chosen flood events.
(b) Runoff discharge and stage records of the chosen events;
(c) Computer simulation of the flood events;
(d) Computer simulation of long term river behavior to determine stretches prone to
meandering, hence needing extra protection;
(e) Changes in alluvial river geometry in terms of aggradation and degradation as
well as lateral channel migration as a result of the flood events;
(f) Design criteria used for the Flood Control Remediation Plan; and
(g) Specific design of the proposed structures including levee protection, riverbank
protection works and protection of bridge crossings and other structures.

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